Film frame counter

ABSTRACT

A film frame counter in which a first optical scanner is arranged to intersect the top half of one sprocket hole when a second scanner intersects the bottom half of another sprocket hole providing signals at a first level when intersecting a sprocket hole and at a second level when not. Because of this arrangement, a unique series of logic transitions occurs in each direction which is detected and the frame count updated only when all transitions have occurred in proper sequence avoiding false counts due to jitter or hunting.

United States Patent 1 Maggi 1 Feb. 19, 1974 FILM FRAME COUNTER [75]Inventor: Charles Robert Maggi, Endicott,

[73] Assignee: The Singer Company, Binghampton,

[ Filed: Dec. 21, 1971 Appl. No.: 210,444

[52] US. Cl. 235/92 V, 235/92 EV, 235/92 PS, 7 a 235/92 12229121925 3-[51] Int. Cl. H03k 21/06 [58] Field of Search235/92 V, 92 PS, 92 SB, 92EV, 235/6l.11 E; 73/157; 340/259, 260; 250/219 11,219 mas/1 .4,, 123;,cease/.19

[56] References Cited UNITED STATES PATENTS 1/1967 Yozo Furukawa et a1.235/92 V 11/1970 Binkley et al. 235/61.11 E

7/1959 Van Haagen 235/92 PK 10/1972 Levy 226/11 Primary ExaminerPaul J.Henon Assistant Examiner-Joseph M. Thesz, 'Jr.

Attorney, Agent, or Firm-John C. Altmiller; James C. Kesterson [5 7ABSTRACT A film frame counter in which a first optical scanner isarranged to intersect the top half of one sprocket hole when a secondscanner intersects the bottom half of another sprocket hole providingsignals at a first level when intersecting a sprocket hole and at asecond level when not. Because of this arrangement, a unique series oflogic transitions occurs in each direction which is detected and theframe count updated only when all transitions have occurred in propersequence avoiding false counts due to jitter or hunting.

8 Claims, 2 Drawing Figures REVERSE FORWARD PATENTEUFEB 19 m4 3793.508

SHEEI 1 0F 2 i REVERSE FORWARD FILM FRAME COUNTER This invention relatesto visual simulation in general and more particularlyto an improved filmframe counter.

Visual systems are used as attachments to flight trainers, drivertrainers, locomotive simultaors, ship simulators, ctc., to provide thetrainee with a more realistic training environment. In many cases thevisual scene is reproduced from information stored on movie film. Such afilm will be normally taken from a vehicle performing the same maneuversin which training is de sired. The film is then played back in thetrainer possibly with some optical transformation to compensate forchanged perspective due to deviations of the simulated vehicle from thetaking path.

In some such systems information relating to the taking position iscoded on the edge of the film so thac deviations from the taking pathmay be computed. An alternative to this is to store such data relatingto the position at which various frames of the motion picture were takenin a computer memory device such as a tape, disk, drum, core, etc. Eachgroup of data will then have associated with it a corresponding framenumber and it is then necessary to know at all times which frame isbeing projected.

Various types of film frame counters have been developed most of whichare subject to occasional errors due to jitter of the film or othercauses. The present invention seeks to overcome these problems byproviding an infallible film frame counter. Although basically intendedfor use in trainer visual systems it will be recognized that the systemmay be used wherever an accurate film frame count is needed.

It is the principle object of this invention to provide an infalliblefilm frame counter.

Another object is to provide such a counter which is bidirectional. Afurther object is to provide such a counter useful in simulator andtrainer visual systems.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the features of construction,combination of elements, and arrangement of parts, which will beexemplified in the construction hereinafter set forth, and the scope ofthe invention will be indicated in the claims.

For a fuller understanding'of the nature and objects of the inventionreference should be had to the following detailed description taken inconnection with the accompanying drawing, in which:

FIG. 1 is partially a perspective and partially a block diagram of thepreferred embodiment of the present invention; and

FIG. 2 is a logic diagram of the logic system used in FIG. 1.

In FIG. 1 is shown a section of the film 11, two sensors l3 and 15,sensor amplifiers l7 and a logic and counter block 19. Sensors 13 and 15may be a Mini- Skanner Micro-Character Detector model 8-3010-3 orequivalent and the amplifiers 17 for use therewith Sensing AmplifierModel Number T-31OD both manufactured by Skan-A-Matic Corp. ofSkaneateles, New York. These sensors transmit a narrow beam of light thereflections of which are picked up by a narrow light receiving fiber inthe center of a bundle of light transmitting fibers having a field ofview of 0.010 inch. Sensors l3 and 15 are arranged'so that the axis 21of sensors 13 will intersect near the top of a sprocket hole 24 ofonefilm frame when the axis 23 of sensor 15 is intersecting near the bottomof a corresponding sprocket hole 25 of an adjoining frame. (Each frameof film in the disclosed embodiment has two sprocket holes associatedwith it.) When axes 21 and 23 intersect the sprocket hole areas noreflections occur resulting in a zero output from the sensors andamplifiers 17. (The area behind the film may be, painted a dull black toabsorb light.) When an axis intersects film a reflection andcorresponding signal from'the sensor 13 or 15 and its associatedamplifier 17 will occur.

Assuming that the film is in the position shown and is moving or beginsto move in the reverse direction, axis 23 will soon intersect film 11and sensor 15 will produce an output signal pulse. At this point theaxis of sensor 13 will still intersect sprocket hole 24 and,consequently,.the sensor output will be zero. If the film is moving orbegins to move forwardly, axis 21 will intersect film l1 and sensor 13will produce an output signal. lf film motion continues in the forwarddirection, axis 23 will intersect hole 27 and the output of sensor 15will go to zero. Shortly thereafter beam axis 21 will intersect hole 29whereupon the output of sensor 13 will drop to zero. The film has nowtraveled the distance between two consecutive sprocket holes andindication thereof may be made by updating a counter as will bedescribed below.

In terms of a truth table with sensor 13 designated A and sensor 15designated B the sequence of events for reverse film movement describedabove is as follows:

For forward movement of film from the position shown in FIG. 1, it canbe seen that the truth table would be:

oo-o

o---oom If a count, forward or backward, may be made to occur only whenthis sequence is followed in the proper order an infallible frame (ormore correctly perforation hole) counter results. A logic circuitfulfilling this requirement will now be described with reference to FIG.2.

The output signals from amplifiers 17 are provided on lines 31 and 33 asinputs to transistor inverters 35, shown in block form, which providebuffering between the amplifiers and the logic. This inversion willinvert the truth tables above. To aid in explaining the logic diagramnew truth tables for forward and reverse are shown on FIG. 2. Throughoutthe explanationinput and output signals will be defined interms of logicl s and 0"s. For the logic shown, a 1" is a positive voltage and a 0 isground potential. It willbe recognized that with other types of logicwhich may equally well be used, other conventions are possible. Itshould also be noted that a transition from 0" to l is a positivegoingpulse.

After each count the logic of FIG. 2 is all in a reset condition.Assuming the same example as above, with the film in the position shownin FIG. 1, sensors lineup with the holes 24 and 25 both-A and B would be1"s. As the filmmoves in' reverse, the first transition to occur is Bgoing from a I This is inverted through inverter 41 causing on line 43to go from a to l This sets latch 45. which has O to l on line 43 theoutput'of latch 45 also goes to one. r

On succeeding transitions A goesfrom 1 to O, B from 0" to 1 and finallyA from 0" to 1 indicating a complete reverse cycle. On this lasttransition 8" will have been a l "on line 39 and when A on line 49 goesto a 1" creating a positive pulse, the l on the D input of'latch 51 istransferred to its 0 output- This output is the second input to AND gate47 which, now with has both inputs present causing itsoutput go from 0"to l, thus providing a down count to a 0" on line 39'.

pulse to a conventional up-down binary counter, 52

e.g., thecounter may comrise a plurality of Texas Instrument CountersSN74'193.

If the film is moved forwardly from the FIG. 1 posi tion instead of inreverse, the first transition'is A" going from 1 to 0- and thus A, online 54 provided by inverter 53, going from 0 to l extant. With a 1 onthe D input of latch 55 from B on line 39 the positive-going 11" pulsecauses the Q output to go to 1. On the last forward transition A" willhave been l at the D input of latch 59. The positive-going pulse whichresults when B goes from 0 to :1 causes the Q output of latch .59 to goto l.

The Q outputs of latches 55 and 59 are the two inputs 7 to AND gate 57causing its output go to l thus providing an up-count pulse to counter52. At the end of 1 either the forward or reverse cycle -1 s are presenton both lines 39 and 49. These are provided as inputs to AND gate 61causing its output to go to l triggering a oneshot 63 set to cause adelay sufficient for the count to be updated. One shot 63 then triggersa oneshot 65 which provides a clear command to latches 45, 51, 5S and 59causing all the Q outputs to go to '0 readying the logic for anothercyclecPulse lengths are, i.e., a a sec. or less that evenif the film ismoving at a high rate no transition will be missed.

The frame count function described so far can'be performed by manywell-known techniques, e.g., using a single light sensor for countingsprocket holes. However, the efficiency and accuracy of such systems isbased on the assumption of smooth and regular film movement while, inactual practice, film for various reasons jitters or oscillates tosomedegree in most film transport systems.

'- In a conventional frame count system, if the film starts to moveforwardly from the FIG. 1 position and all but the last transition isaccomplished, a count would result since all the additional movementrequired is less than one-half a sprocket holewidthlf the film nowreverses to return to the starting position, a false count, or even twofalse counts would result because a conventional counting system wouldAND a direction command with a frame or-sprocket hole count. During thisperiod the commanded direction whether with or without acount.

would remain the same, cg, forward. As the film moved forwardlycrossingamark or sprocket hole a first pulse would result and-whenit wenthackfaseeondm Thus the system wouldrecord two forward pulses.

However, in the systemcof. thepresent invention no count occursinsuchasituation; theifilmg moves. backwardsthrough. the 'transitionlatch 51will, beset I D input. vBut latches 45 and 59Iwilln'ever have theirconditions met and no count occurs either forwarder reverse. inlikemanner, when moving in reverse, movement'to the point of countingandasre'turn-twill not, 7

cause a count. I, a a a p I Examination of the" truthtables makes'itclear that only if the required transitions occur in the proper orderwill the count conditions be satisfied. The first latch in eachcase,.i;e., 45'and indicates thataa for ward or reverse cycle hasstartedcThe second latch, i. e., 51 and 59 incidates the endof thecycle. Only if the direction of film movement in which the "l", 3" lcondition isle-ft is the same direction as that condition is re-eneterdwill a' count occur, The reset logic associatedwith gate 61 assures afresh start each condition is entered Block 67 represents means toreset'counterc52. This may be a simple reset switch to reset all theflip-flops in the counter or may be an automated reset commandintegrated into the film system. The frame count in binary form istakenoff on a plurality of lines indicated by line 69 on the drawing Thefirst stage, i.e., 20, of the counter will not be output with the secondstage,i. e., 2 being considered the 2 output to accomplish a'division bytwo. This is required since normally there are two sprockets per frame.if otherwise, a proper divide by N counter may beused when N is thenumber of sprocket hoels per frame. r

The output of the counter may be decoded and displayed in base 10 formby conventional circuitry and/or displays and/or may be used in the filmdrive system if I required, e.g,, for comparison with a d esired framecount to develop an error signal. 7

Thus a film frame counter which provides an accurate count irrespectiveoffilm jitter or oscillation has been shown. Although'aspecific'embodiment has been shown and described various modificationsmay be made without departing from the spirit of the invention which isintended to be limited solely by the appended claims. 7 7 V V V 7 Whatis. claimed is: V i V V r a l. A film frame counter forruse. with amotion picture projector comprising:

a. a first sensor to sense a sprocket hole by sensing'an,

area lessthan one-half the length of a sprocket hole and arranged in afixed position where it will intersect only the top half of a firstsprocket hole when the film is in a predetermined position; 7 b. asecond similar sensor arranged to intersect only the bottom half of asecond sprocket hole when i. said first and second sensors providesimultaneous outputs at said first level;

2. said first sensor provides an output at said second level while theoutput of said second sensor remains at said first level;

3. said first and second sensors provide an output at said second level;

4. said first sensor provides an output at said first level while saidsecond sensor remains at said second level; and

5. said first and second sensors provide an output at said first level;

and a reverse count pulse only when the following outputs occur in thelisted order:

1. said first and second sensors provide simultaneous outputs at saidfirst level;

2. said second sensor provides an output at said second level while theoutput of said first sensor remains at said firstlevel;

3. said first and second sensors provide an output at said second level;

4. said second sensor provides an output at said first level while saidfirst sensor remains at said second level; and

5. said first and second sensors provide an output at said first level;and

d. a divide-by-N up-down counter having said count pulses as inputs; Nbeing equal to the number of sprocket holes per frame of film.

2. The invention according to claim 1 wherein said responsive meanscomprise means to sense a transition of said first sensor from saidfirst to said second level while said second sensor is at said firstlevel and to sense the transition of said second sensor from said secondto said first level while said first sensor is at said first level toindicate that the outputs have occurred in the proper order for aforward count and to sense the transition of said second sensor fromsaid first to said second level while said first sensor remains at saidfirst level and to sense the transition of said first sensor from saidsecond to said first level while said second sensor is at said firstlevel to indicate that the outputs have occurred in the proper order fora reverse count.

3. The invention according to claim 2 wherein said responsive meanscomprise:

a. a first inverter having its input connected to the output of saidfirst sensor;

b. a second inverter having its input connected to the output of saidsecond sensor;

c. a first latch, having a data input and a load input operable such.that a transition from said second level to said first level will causethe level on said data input to be provided at the output of said latch,with its data input connected to said first sensor and its load input tothe output of said second inverter;

d. a second similar latch having its data input connected to saidsecond'sensor and its load input to said first sensor;

e. a first AND gate having the outputs of said first and second latchesconnected to its inputs and having its output connected to the downinput of said counter;

f. a third similar latch having its data input connected to said secondsensor and its load input to said first inverter;

g. a fourth similar latch having its data input connected to said firstsensor and its lead input to said second sensor; i

h. a second AND gate having the outputs of said third and fourth latchesas its inputs and having its output connected to the up input of saidcounter;

i. a third AND gate having as its two inputs theoutputs of said firstand second sensors; and

j. delay means having as an input the output of said third AND gate andproviding as an output, a predetermined time after an input appears, ashort pulse said output being connected to a reset input on said first,second, third, and fourth latches to cause their outputs to go to saidsecond level.

4. The invention according to claim 3 wherein said delay means comprise;

a. a first one-shot multivibrator having its input connected to saidthird AND gate and providing an output a predetermined time after aninput appears; and

b. a second oneshot multivibrator having its input connected to theoutput of said first multivibrator to provide, on occurrence of aninput, a pulse of predetermined length,

5. The invention according to claim 1 wherein said first and secondsensors comprise:

a. means to illuminate the sprocket hole area of said film on a firstside;

b. light absorbing means placed on the other side of said film; and

c. light sensing means having an input field of view less than onehalfsprocket hole length.

6. The invention according to claim 5 wherein said sensing means andilluminating means comprise a micro-character detector having a bundleof light transmitting fibers to provide illumination arranged around alight receiving fiber aligned with said sprocket holes and amplifyingmeans to amplify the sensed signal and provide outputs-at said firstlevel when a low light -level is received and at said second level whena high light level is received.

7. A method of counting film frames comprising:

a. establishing a reference film frame position;

b. aligning first and second sensing means which detect an area lessthan one half sprocket hole so that when the'film is in said referenceposition said first means will be aligned with the top half of onesprocket hole and said second means with the bottom half of a secondsprocket hole whereby if presence of a sprocket hole is designated alogic 1 and absence of a sprocket hole and logic 0 displacement of thefilm in one direction by the dis tance equal to the sprocket holespacing causes the first and second sensing means to have outputsfollowing a first order 1, l;0,l ;0,0;l,0; and L1 and in the otherdirection following a second order 1,l',l,0;0, 0;(), l; and 1,1;

c. sensing the order and occurrence of said logic states and providing,to an up-down counter, a count in one direction only when said firstorder occurs and in another direction only when said second orderoccurs; and

d. dividing the count in said counter by the number of sprocket holesper frame of film.

8. The invention according to claim 7 wherein sensing said orders isaccomplished by sensing only the first and last transitions in saidfirst and second orders whereby a transition of said first sensor from 1to while the second remains at l and of said second sensor,

0nd sensor from 1 to 0 while said first sensor is l and of said firstsensor from 0 to '1 while said second sensor is 1 will result in a countin said other direction.

. V UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION Patent No.3.793508; Dated RFebruary 19 J-974;

lnvent fls) Charles Maggi It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 1 line 18, "thac" should be -that--.

Co1unu12QlUne 1, USOPSH shoukibe --sor--.

Column 3, line 47, after "are" insert "short enough".

Column 4, line 31, "20" should be --2--,

Signed, and sealed this 2nd day of July 1-974.

(SEAL) Atteet: Q EDWARD M. FLETCHER,JR. f JC.MARS LL-DA N AttestingOfficer .Commissloner i a t

1. A film frame counter for use with a motion picture projectorcomprising: a. a first sensor to sense a sprocket hole by sensing anarea less than one-half the length of a sprocket hole and arranged in afixed position where it will intersect only the top half of a firstsprocket hole when the film is in a predetermined position; b. a secondsimilar sensor arranged to intersect only the bottom half of a secondsprocket hole when said film is in said predetermined position, each ofsaid sensors providing an output at a first level when intersecting asprocket hole and at a second level when not sensing a sprocket hole; c.means responsive to the outputs of said first and second sensors toprovide a forward count pulse only when all of the following sensoroutput signals occur in the listed order:
 1. said first and secondsensors provide simultaneous outputs at said first level;
 2. said firstsensor provides an output at said second level while the output of saidsecond sensor remains at said first level;
 3. said first and secondsensors provide an output at said second level;
 4. said first sensorprovides an output at said first level while said second sensor remainsat said second level; and
 5. said first and second sensors provide anoutput at said first level; and a reverse count pulse only when thefollowing outputs occur iN the listed order:
 1. said first and secondsensors provide simultaneous outputs at said first level;
 2. said secondsensor provides an output at said second level while the output of saidfirst sensor remains at said first level;
 3. said first and secondsensors provide an output at said second level;
 4. said second sensorprovides an output at said first level while said first sensor remainsat said second level; and
 5. said first and second sensors provide anoutput at said first level; and d. a divide-by-N up-down counter havingsaid count pulses as inputs, N being equal to the number of sprocketholes per frame of film.
 2. The invention according to claim 1 whereinsaid responsive means comprise means to sense a transition of said firstsensor from said first to said second level while said second sensor isat said first level and to sense the transition of said second sensorfrom said second to said first level while said first sensor is at saidfirst level to indicate that the outputs have occurred in the properorder for a forward count and to sense the transition of said secondsensor from said first to said second level while said first sensorremains at said first level and to sense the transition of said firstsensor from said second to said first level while said second sensor isat said first level to indicate that the outputs have occurred in theproper order for a reverse count.
 2. said first sensor provides anoutput at said second level while the output of said second sensorremains at said first level;
 2. said second sensor provides an output atsaid second level while the output of said first sensor remains at saidfirst level;
 3. said first and second sensors provide an output at saidsecond level;
 3. said first and second sensors provide an output at saidsecond level;
 3. The invention according to claim 2 wherein saidresponsive means comprise: a. a first inverter having its inputconnected to the output of said first sensor; b. a second inverterhaving its input connected to the output of said second sensor; c. afirst latch, having a data input and a load input operable such that atransition from said second level to said first level will cause thelevel on said data input to be provided at the output of said latch,with its data input connected to said first sensor and its load input tothe output of said second inverter; d. a second similar latch having itsdata input connected to said second sensor and its load input to saidfirst sensor; e. a first AND gate having the outputs of said first andsecond latches connected to its inputs and having its output connectedto the down input of said counter; f. a third similar latch having itsdata input connected to said second sensor and its load input to saidfirst inverter; g. a fourth similar latch having its data inputconnected to said first sensor and its load input to said second sensor;h. a second AND gate having the outputs of said third and fourth latchesas its inputs and having its output connected to the up input of saidcounter; i. a third AND gate having as its two inputs the outputs ofsaid first and second sensors; and j. delay means having as an input theoutput of said third AND gate and providing as an output, apredetermined time after an input appears, a short pulse said outputbeing connected to a reset input on said first, second, third, andfourth latches to cause their outputs to go to said second level.
 4. Theinvention according to claim 3 wherein said delay means comprise; a. afirst one-shot multivibrator having its input connected to said thirdAND gate and providing an output a predetermined time after an inputappears; and b. a second one-shot multivibrator having its inputconnected to the output of said first multivibrator to provide, onoccurrence of an input, a pulse of predetermined length.
 4. said firstsensor provides an output at said first level while said second sensorremains at said second level; and
 4. said second sensor provides anoutput at said first level while said first sensor remains at saidsecond level; and
 5. said first and second sensors provide an output atsaid first level; and d. a divide-by-N up-down counter having said countpulses as inputs, N being equal to the number of sprocket holes perframe of film.
 5. said first and second sensors provide an output atsaid first level; and a reverse count pulse only when the followingoutputs occur iN the listed order:
 5. The invention according to claim 1wherein said first and second sensors comprise: a. means to illuminatethe sprocket hole area of said film on a first side; b. light absorbingmeans placed on the other side of said film; and c. light sensing meanshaving an input field of view less than one-half sprocket hole length.6. The invention according to claim 5 wherein said sensing means andilluminating means comprIse a micro-character detector having a bundleof light transmitting fibers to provide illumination arranged around alight receiving fiber aligned with said sprocket holes and amplifyingmeans to amplify the sensed signal and provide outputs at said firstlevel when a low light level is received and at said second level when ahigh light level is received.
 7. A method of counting film framescomprising: a. establishing a reference film frame position; b. aligningfirst and second sensing means which detect an area less than one halfsprocket hole so that when the film is in said reference position saidfirst means will be aligned with the top half of one sprocket hole andsaid second means with the bottom half of a second sprocket hole wherebyif presence of a sprocket hole is designated a logic ''''1'''' andabsence of a sprocket hole and logic ''''0'''' displacement of the filmin one direction by the distance equal to the sprocket hole spacingcauses the first and second sensing means to have outputs following afirst order 1, 1;0,1;0,0;1,0; and 1,1 and in the other directionfollowing a second order 1,1;1,0;0, 0;0, 1; and 1,1; c. sensing theorder and occurrence of said logic states and providing, to an up-downcounter, a count in one direction only when said first order occurs andin another direction only when said second order occurs; and d. dividingthe count in said counter by the number of sprocket holes per frame offilm.
 8. The invention according to claim 7 wherein sensing said ordersis accomplished by sensing only the first and last transitions in saidfirst and second orders whereby a transition of said first sensor from 1to 0 while the second remains at 1 and of said second sensor from 0 to 1while said first sensor is 1 will result in a count in said onedirection and a transition of said second sensor from 1 to 0 while saidfirst sensor is 1 and of said first sensor from 0 to 1 while said secondsensor is 1 will result in a count in said other direction.